题目描述

A linked list consists of a series of structures, which are not necessarily adjacent in memory. We assume that each structure contains an integer key and a Next pointer to the next structure. Now given a linked list, you are supposed to sort the structures according to their key values in increasing order.

输入格式

Each input file contains one test case. For each case, the first line contains a positive N ($<10^5$) and an address of the head node, where $N$ is the total number of nodes in memory and the address of a node is a 5-digit positive integer. $NULL$ is represented by −1.
Then $N$ lines follow, each describes a node in the format:

Address Key Next

where Address is the address of the node in memory, Key is an integer in $[−10^5 ,10​^5 ]$, and Next is the address of the next node. It is guaranteed that all the keys are distinct and there is no cycle in the linked list starting from the head node.

输出格式

For each test case, the output format is the same as that of the input, where $N$ is the total number of nodes in the list and all the nodes must be sorted order.

测试输入：

5 00001
11111 100 -1
00001 0 22222
33333 100000 11111
12345 -1 33333
22222 1000 12345

测试输出：

5 12345
12345 -1 00001
00001 0 11111
11111 100 22222
22222 1000 33333
33333 100000 -1

代码

#include <cstdio>
#include <stdlib.h>
#include <algorithm>
using namespace std;
const int maxn = 100001;struct Node {int address;int data;int next;bool flag;
} node[maxn];bool cmp(Node a, Node b) {if (a.flag == false || b.flag == false) {return a.flag > b.flag;} else {return a.data < b.data;}
}int main() {for (int i = 0; i < maxn; i++) {node[i].flag = false;}int n, start_address;scanf("%d%d", &n, &start_address);int address;//对输入数据的定义for (int i = 0; i < n; i++) {scanf("%d", &address);scanf("%d%d", &node[address].data, &node[address].next);node[address].address = address;}/** 这一步是很关键的，怎么知道输入的数据有多少是在链表中？*/int count = 0, p = start_address;while (p != -1) {node[p].flag = true;count++;p = node[p].next;}if (count == 0) {printf("0 -1");} else {sort(node, node + maxn, cmp);printf("%d %05d\n", count, node[0].address);/** 防止-1被 %05d 格式化，需要提前判断 */for (int i = 0; i < count; i++) {if (i != count-1) {printf("%05d %d %05d\n", node[i].address, node[i].data, node[i+1].address);} else {printf("%05d %d -1\n", node[i].address, node[i].data);}}}return 0;
}

所学

采用静态链表(类似数组)，因为$N<10^5$，所以当给静态数组分配的存储空间使用不完时，必然会影响sort()函数的排序，因此得通过cmp进行二级排序，找出真正存有数据的链表结点。